Indicating device for telemeters.



' 0. EPPENSTEIN.

INDICATING DEVICE FOR TELEMETERS.

APPLICATION man APR-8.19l5.

1 15 11,, Patented; (m. 26, 1915.

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OTTO EPJPIENSTEIN, 03? JENA, GERI'KANY, ASSIGNOR TO THE FIRM 0F GARL ZEISS, 0F JENA, GERMANY.

INDICA'IING DEVICE FGE. TELEME'IElEt-S,

mum-um Specification of Letters Patent.

Patented @ct. 2d, 1915,

Application filed April 8, 1915. Serial No. 20,071.

To all whom it may concern:

lrle it known that I, Orro Erritusrnim a citizen of the German Empire, residing'at Jena, Germany, have invented a new and useful Indicating Device for Telemeters, of which the following is a specification.

The invention relates to an indicating device for telemeters having the base-line within the instrument, in which the distance to be measured is determined by setting a measuring device, the movement of which efiects a mutual displacement of two images presented to the observer and takes place essentially proportional to the quan tity of the angle of the triangulation at the aiur- If in such telemeters the measuring device is direct connected with a scale divided according to the distance, an unequal division of the scale is the result as it is Well known t rat the distance to be determined is inverseproportional to the angle at the aint.

The invention permits to replace thisunequal scale in a simple way without mechanical means of transmission by \an equally divided scale or to connect it with such, via, to transfer the movement of the measuring d vice into a quantity proportional to the distance to be measured. Th s is obtained by connecting the measuring device with. a variable electric resistance in such a way that the quantity. of the resistance alters in proportion to the movement of the measuring device. In different ways a transformation oi the quantity of this variable resistance can then be eii'ected into a corresponding quantity of inverse proportion.

A particularly simple arrangement is cffected by putting the variable resistance into a circuit, passed by a current of constant tension. ll ith such an arrangement, as is well known the produced strength of the (current is always inverse proportional to the existing resistance, that 1s to say the strength or" the current means practically a quantity proportionalv to the distance. It

is only necessary to put into the circuit an instri'nnent for measuring the strength of the current and having an index moving in proportion to the strength of the current, the scale being divided direct according to the distance Such an indicating device ollers the f her advantage to allow the reading scale to be fired at any place, even to provide by this means a telemeter with several reading scales, which can be read simultaneously. The adjustment of the indicating device can be made by altering the quantity of an additional resistance put into the circuit. If no current of constant tensionis, at hand, the transformation of the variable resistance into a reciprocate quantity can be effected by means of a lVheatst-one bridge. Ii in a VVheatstone bridge two opposite ln-anches have constant resistance and the resistance in the two other branches is al tered, the product of the resistance in the two other branches must always remain constant it the Zero line of the bridges is to remain without current; therefore in, these two branches the resistance of the one must be inverse proportional. to that of the othein F or this reason the resistance influenced by the measuring device of the telemeter will be arranged as branch of ll heatstone bridge with which two branches of constant resistance are connected, while the fourth branch of the bridge opposite the first branch is provided with a resistance of ad justable quantity. Care must then be taken by altering the resistance in the fourth branch, that the zero line of the bridge remains always without current; if this is the case the resistance in the fourth branch represents a quantity proportional to the distance to be measured. If the resistance of the fourth branch is torn-led of a Wire of constantsection, the wire may be fitted With a scale, divided direct according to the dis tance. In this case again the reading scale with the resistance belonging to it maybe fixed at any place desired. For purposes of adjustment it is sufiicient to alter the quantity of any resistance of the bridge. The adjustment of the resistance in the fourth branch of the bridge may take place autonmtically by putting a relay in the zero line of the bridge, which, as soon as the current passes the zero line, actuates a device increasing or diminishing the resist ance in the fourth branch according to the direction of the current in the Zero line.

In the drawing two constructional examples of the invention are each shown dia grammatically Figure 1 relates to an arrangement in which the resistance influenced by the mess Elli] uring device of the telemeter alters the strength of a current of constant tension. 111g. 2 shows an example in which this re- In both figures a telemeter is dealt with in which the measuring-device is termed by a glass wedge a. disposed displaceably in the direction of the optical axis of the telemeter, the ax s being indicated by the dotted line A-1L The mounting a of the glass wedge a, in both figures connected with a pulley b, which in .case the glass wedge a is displaced, can roll. along a resistance wire 0 stretched between two binding screws 0 and 0 ()n the hearing if of the pulley Z), arod b of conducting material is lined which can slide in a fixed guide (Z. If a current is "put in circuit at the binding screw 0 it flows according to the positionof the pulley Z) and therefore of the glass wedge (0 through a corresponding part of the wire 0 and then through the pulley Z) and the sliding rod I)", the resistances of which are practically zero, to the guide (Z. Therefore, the

alteration of the resistance in a current between the binding screw 0 and the guide d is proportional to a displacement of the glass wedge a.

In Fig. 1 the binding screw 0 and the: guide (Z are put in a. circint which receives current of constant tension from battery 6. An ampcremeter f provided with a distance scale and. a resistance box 9 for adjustment are placed into the circuit. The resistances of the connecting lines, shown heavy in the drawing, are infinitesimal as compared with the resistance of the wire 0. If in this arrangement the' glass wedge a, is displaced and thereby the resistance in the circuit is altered, the strength of the current alters in inverse proportion, the amperemeter shows, therefore, a quantity proportional to the dis tance to be measured.

In the example shown in Fig. 2 the parts between the binding screw 0 and the guide (i form a branch of a W heatstone bridge. A resistance h is connected with the binding screw 0 and a resistance with the guide (I, the resistances forming each .an adjacent branch of'the bridge, .while the opposite fourth branch. is composed in similar manner as the first branch. Between two binding screws in and 1: a resistance wire 76 is drawn, along which slide a pulley fixed on a guide rod Z. The guide rod Z slides in a guide m. which is in conducting connection with the resistance 71,: the bind ing screw is connected with the resistance 11. Next the wire 70 tl ere is an equally divided scale n, on which plays an index i? fixed to the bearing of the pulley Z. A galvanometer 0 is put into the Zero line of the bridge between the guides (Z and m the gelvanoinctcr being developed as a double acting relay. For this purpose it is provided at both sides of its index with contacts o and 0 which are connected with the outer bimling screws 7/ and y) of an clcctromotor which 2-:11'1 turn to both sides. The middle bindin screw 7) of the motor p is connected. with a battery 0, the other pole of which is coin'iected up with the index of the galvanometer o. ()n til, axis of the motor 7 a toothed wheel 71 is mounted, gearing with a rack 1 which again is rigidly coniwctcd with the guide rod 6 bearing the pulley t. The whole arrangement of the bridge is put into the circuit of a battery by means of the binding screws 0 and AF. 'lhe resistances ot the coi'inecting line shown heavy in the drawing are infinitesimal as compared with the resistances h and 21 and the resistances oi the wires 0 and. Z1. This arrangcment eiiects that with each displacement of y the glass wedge (1 the resistance in the wire in is always set automatically to a quantity which is inverse proportional. to the quantity of the resistance in the wire 0. For as soon as a displacement of the gin wedge (I. alters the resistance in the-wire (I, there will be current in-thc zero line of the bridge and according to the direction of the current one of the contacts 0 or 0 of the galvunomcter is closed. The motor 7) therefore turns in one sense or the other and thus displaces by means of theraclt r and the guide rod 1 the pulley Z on fthe wire A: so long until the bridge is again without current, that is to say until the resistance of the wire K: has again reached a quantity which is inverse proportional to the quantity of the resistance in the wire hcrciore the length of the part of the" wire it: under current is a quantity proportional to the distance to be n'ieasured and the equally divided scale 11. can

-be numbered direct accordingto the distance.

essentially proportional to the quantity of the angle of triangulai on at the said object a current source, an indicating instruu'ient and a variable electric resistance, the said cnrrent-smircc, the said indicating instruinent and the said resistance being connected together by a \Yhcatstonc bridge. a branch o"- which is formed by the variable resistance, while the branches adjacent to the said b anch have constant resistance and the branch opposite to the said branch is adjustable, the said measuring device he mg coupled with thesild resistance in such a manner that. the resistance alters in proportion to the movement ot the measuring device. I

2. The combination with e telemeter adapted to present to en ebservertwo images of en lcbject, the distance of which is to be measured, cf a measuring device novably fitted Within the said telemeter and v l it =adapted to eflect a mutual v(i sfilaeement of the szngl two images, the increment ne essary for bringing the said measuring from its infiniteposition to the position pertaining to the distahce of the seid ebject being essentially proportional to the quantity 0f the angle of triangulation at the said object, a current-source, an indicating instrument and a variable electric resistance, the said interim current-source, the said. indicating instrument and the said resistance being connected together by a Wheatstcne bridge, a branch of which is formed by theiveriziele resistance, While the branches adjacent to the said branch have constant resistance and the v in such a manner that the resistance eltevs in preportien t0 the movement of the messuring device.

- OTTQ EPPENSTEIN. "Witnesses I PAU 1 Kni'iem, I li-ICHAIU) HAHN. 

